Saturday, March 26, 2011

And Now...Becquerels!

Some of the news reports are giving the radioactivity of water and soils in Becquerels. Those numbers are likely to be big. A Becquerel is one count per second, or one alpha, beta, or gamma per second.

Becquerels do not translate simply into the dose units of Sieverts, which I've mentioned in several previous posts. Sieverts measure biological effect, and alphas, betas, and gammas have different effects.

Each count represents a single atom. For comparison, in a cubic centimeter of water (about a tablespoon), there are about 3 x 1022 molecules, or 1023 atoms. A billion is 109. The superscripts indicate the number of zeroes after the first number (assumed to be 1 in the last two numbers).